Bagless vacuum cleaner

ABSTRACT

In a bagless vacuum cleaner, comprising a cyclonic separator having a cyclone tube ( 6 ), and a bucket ( 3 ) for containing a liquid, a diameter of the bucket ( 3 ) is at least 2 times a diameter of the cyclone tube ( 6 ). Preferably, in the bucket ( 3 ) there is a body ( 8 ) having a center in line with a center of the cyclone tube ( 6 ), a shape of the body ( 8 ) being or approximating a mushroom-shape.

FIELD OF THE INVENTION

The invention relates to a bagless vacuum cleaner using a cyclone toseparate dust from air.

BACKGROUND OF THE INVENTION

US 2012/0145009 discloses a wet type dust collecting apparatus of avacuum cleaner, which includes a first separating unit configured tofilter out and discharge dust by rotating air which is inlet via a firstair inlet, and a plurality of a second centrifugal separating unitsconfigured to filter out dust from the air which is discharged from thefirst separating unit, and configured to eliminate dust from the inletair via water which is filled inside of the second centrifugalseparating units.

SUMMARY OF THE INVENTION

It is, inter alia, an object of the invention to provide an improvedvacuum cleaner. The invention is defined by the independent claims.Advantageous embodiments are defined in the dependent claims.

In one aspect of the invention, in a bagless vacuum cleaner, whichcomprises a cyclonic separator having a cyclone tube, and a bucket forcontaining a liquid, a diameter of the bucket is at least 2 times adiameter of the cyclone tube. Preferably, in the bucket there is a bodyhaving a center in line with a center of the cyclone tube, a shape ofthe body being or approximating a mushroom-shape.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first embodiment of the invention;

FIG. 2 shows a first set of dimensions of an embodiment of theinvention;

FIG. 3 shows preferred dimensions of an embodiment of the invention; and

FIG. 4 shows a preferred embodiment of the invention having a rim shapedto regulate an amount of liquid entering into a cyclone tube.

DESCRIPTION OF EMBODIMENTS

Vacuum cleaners are available in two basic versions: bag and bagless.The bagless versions are based on dust separation by cyclonic action,filters, water filtration, and combinations of these systems.

Water filtration uses water as the main filter medium. Air is forcedinto the water where particles are captured in the water as the airmoves through. Instead of water, another cleaning liquid could be used.

In cyclonic systems, centrifugal forces are created by rotating airinside a chamber. A high speed rotating (air)flow is established withina cylindrical or conical container called a cyclone. Air flows in ahelical pattern, beginning at the top of the cyclone and ending at thebottom end before exiting the cyclone through the center of the cycloneand out the top. Particles in the rotating stream have too much inertiato follow the tight curve of the stream, and strike the outside wall,then fall to the bottom of the cyclone where they can be removed. Thecyclone geometry, together with flow rate, defines the cut point of thecyclone, i.e. the size of particles that will be removed from the streamwith a 50% efficiency.

In order to get the best performance out of the vacuum cleaner, thechallenge is to attain the highest separation performance while having apressure drop in the system which is as low as possible. Normally ahigher separation performance comes with a higher pressure drop whichresults in a lower suction power and therefore less performance for thevacuum cleaner. Therefore this invention focuses on a better filterperformance without compromising on suction power performance.

As described above the particles in the rotating stream which have toomuch inertia to follow the tight curve of the stream will strike theoutside wall. Then they fall to the bottom of the cyclone where they arestored while the clean air leaves the cyclone in the middle sectionthrough a so-called vortex finder. However, some of the particles whichstrike the outside wall are dragged back from the wall into the centerof the cyclone by small air movements (turbulences) which occur.Furthermore it is hard to keep the particles at the bottom of thecyclone in the dust collecting space as even very small flow velocitiescan pick them up and drag them to the cyclone again. These phenomenaboth decrease the separation performance of the cyclone.

FIG. 1 shows a first embodiment of the invention, in which water 7 isprovided at the bottom of the cyclone, such that particles are trappedby the water are prevented from being introduced to the cyclone again.Furthermore a part of the cyclone wall is wetted in the process, causingparticles to first stick to the wall and then being rinsed towards thebottom of the cyclone where the dirt collecting finds place.

A cyclone is placed such that a dirt bucket 3 is located at the bottomof the cyclone. When filled with water 7, a vortex finder 5 is pointingtowards the water. Dirty air 1 is sucked directly in the cyclone. Dustand air are separated in the cyclone. The dust particles flow with theair stream 2 downwards along the wall of a cyclone tube 6 and fall inthe water at the bottom of the bucket 3. Clean air 4 is sucked via thevortex finder towards a suction motor (not shown). The diameter of thebucket 3 is larger than the diameter of the cyclone tube 6.

FIGS. 2 and 3 show relative dimensions of embodiments of the invention.When the diameter of the bucket is decreased, the water rotational speedincreases and as a result the water gets more turbulent. Therefore thedistance from the water to the top of the vortex finder 5 needs to beincreased to avoid water being sucked into the vortex finder 5. Thisresults in an increase of the total height of the appliance. Putotherwise, an increased width of the bucket 3 allows for a reduction inits height with the same amount of water.

Preferably, there is at least 0.5 liter of water in the bucket. Asmaller diameter combined with the requirement of 0.5 liter of waterresults in a higher bucket to allow the 0.5 liter water storage.

Taking into account an optimal height of a vacuum cleaner to guarantee astable appliance (not tilting when being moved), the dimensioning shownin FIG. 2 appeared very beneficial, while that of FIG. 3 is even morepreferred. The following table compares the relative dimensions of FIGS.2 and 3 to those in of an actual embodiment of a Samsung vacuum cleaneras covered by US 2012/0145009.

FIG. 2 FIG. 3 US 2012/0145009 Diameter of cyclone tube 6 in 100/200 =100/240 = 100/172 = relation to diameter of bucket 0.5 0.4 0.58 3Diameter of bucket 3 in 200/70 = 240/80 = 172/121 = relation to distancebetween 2.8 3.0 1.4 bottom of bucket 3 to end of vortex finder 5Diameter of cyclone tube 6 100/55 = 100/70 = unknown in relation todistance 1.8 1.4 between water surface to end of vortex finder 5

The end of the vortex finder 5 is understood to be the lowest part whereair can enter into the vortex finder 5.

Challenge in a cyclonic system containing water (either that of theprior art or that of FIG. 1) is to keep the water away from the suctionmotor. Normally the cyclonic action takes care of this by centrifugingwater droplets to the outside walls in a way that air and water areseparated before air enters the vortex finder. The force responsible forseparating the water droplets from the air is the centrifugal force. Theforce is given by:

Fc=mω ² r(ω=angular velocity, m=mass, r=distance relative to center ofthe cyclone)

From the formula it follows that when the distance to the centerapproaches zero, the resulting force also goes to zero. Therefore,droplets at the center do not experience centrifugal forces and are notseparated from the air. This can result in water droplets being suckedfrom the center passing the vortex finder into the suction motor.

As soon as the system of FIG. 1 has been started up, no water exist atthe center because of the rotation of the water in the dirt bucket 3(comparable with a whirlpool). Water in the dirt bucket 3 rotates and adry spot occurs at the middle. However, when starting the appliance thewater is not rotating yet and therefore the dry spot is not yet createdand water is sucked up through the vortex finder into the suction motor.

To that end, the embodiment of the invention as shown in FIG. 2comprises a body 8 with a specific shape which prevents water from beingpresent in the middle of the dirt bucket 3 at startup which is notinterfering with the cyclone when the system is in steady state. It isnoted that the advantages of this particular shape can be used both inthe embodiment of the invention of FIG. 1 and in the prior art as shownin e.g. US 2012/0145009.

A preferred shape of the body 8 is the shape of a mushroom as shown inFIG. 2. In this shape there is no ‘flat spot’ (such as when the bodywould have a flat upper surface) where water can accumulate and stillthe center of the space below the cyclone is ‘filled’ till such anextent that the water present will always experience centrifugal forces.A mushroom-like kind of shape as shown in FIG. 2 will not function asvortex stabilizer, which would happen if the body would have atriangular shape above the water surface).

The mushroom-shaped body 8 should not touch the vortex finder 5 or betoo close to the vortex finder 5 as capillary forces between surface ofthe mushroom-shaped body 8 and the vortex finder 5 surfaces will ‘catch’water. This will result in water being sucked up through the vortexfinder 5.

A pure triangular form would result in that water gets the opportunityto be sucked up along the slope of the triangular body entering thevortex finder 5. Especially when the water is moving because of movementof the appliance, water will be present at the slopes and can thuseasily be sucked up. However, it is possible for the body to havemultiple slopes, e.g. a first slope at an angle of less than 45° (e.g.20°) with the horizontal at an uppermost part of the body, followed by asecond slope at an angle of more than 45% (e.g. 70°) with thehorizontal: this would approximate the ideal mushroom shape.

Furthermore the body 8 preferably has a part 9 having a smaller diameter(as shown in FIG. 2). This part (recess) 9 should have the same heightas the height of the water. This feature prevents water from easilybeing forced towards the slope of the body when the appliance ismoved/shaken.

Another challenge in a cyclonic system combined with water is to keepthe system as clean as possible. The less parts that get dirty, the moreconvenient the appliance will be with regard to cleanability.

The amount of contamination of the cyclonic parts is highly dependent onthe amount of water entering the cyclone from the dirt container 3. Ifmore water enters the cyclone tube 6, more of it becomes wet andtherefore dirty. A similar kind of relation can be found for theseparation performance, which is also highly dependent on the amount ofwater in the cyclone. The wetter the cyclone gets, the better theseparation performance will be.

From a consumer point of view the separation performance should be asgood as possible while the appliance should stay as clean as possible.This results in a contradiction for the preferred amount of waterentering the cyclone.

To set for the optimum one would like to be able to control the amountof water going to the cyclone.

In an embodiment without a rim 10 as shown in FIG. 2, water will beblown towards the top of the dirt container 3 from which it will besucked into the cyclone tube 6 by a secondary flow going from the middleof the cyclone via top of the bucket into the cyclone again. The amountof water going to the cyclone is not controllable in such an embodimentwithout a rim 10.

As a result of the rim 10 in FIG. 2, water travels from the top cover ofthe bucket 3 to the rim 10 where the steep corner combined withgravitational forces force the water to fall off the rim. The rotationalair centrifuges the water then away from the cyclone. This solutiongives a minimum amount of water entering the cyclone. As shown in FIG.2, the rim 10 is positioned at the end of the cyclone tube 6 at thetransition of the cyclone tune 6 to the dirt container 3.

The rim 10 is preferably higher than 1 mm and should have a sharp edgedend. In an embodiment, the rim 10 has openings 11 to give part of thewater the ability to enter the cyclone tube 6. The number and shape ofsuch openings 11 allow for regulating an amount of water that enters thecyclone tube 6.

The invention may be used in an optimal setting containing water in thebucket 3, as well as in a suboptimal setting where there is no water inthe bucker 3, depending on the preference of the consumer.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.The word “comprising” does not exclude the presence of elements or stepsother than those listed in a claim. The word “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.In the device claim enumerating several means, several of these meansmay be embodied by one and the same item of hardware. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage.

1. A bagless vacuum cleaner, comprising a cyclonic separator having acyclone tube, and a bucket for containing a liquid, wherein a diameterof the bucket is at least 2 times a diameter of the cyclone tube.
 2. Abagless vacuum cleaner as claimed in claim 1, wherein the diameter ofthe bucket is 2.5 times the diameter of the cyclone tube.
 3. A baglessvacuum cleaner as claimed in claim 1, wherein the diameter of the bucketis at least 2.8 times a distance between the bottom of the bucket to anend of a vortex finder of the cyclonic separator.
 4. A bagless vacuumcleaner as claimed in claim 3, wherein the diameter of the bucket is atleast 3 times the distance between the bottom of the bucket to the endof a vortex finder of the cyclonic separator.
 5. A bagless vacuumcleaner as claimed in claim 1, wherein in the bucket there is a bodyhaving a center in line with a center of the cyclone tube, a shape ofthe body being or approximating a mushroom-shape.
 6. A bagless vacuumcleaner as claimed in claim 5, wherein the body has a part having asmaller diameter than a largest diameter of the body, a height of thepart corresponding to an intended level of the liquid.
 7. A baglessvacuum cleaner as claimed in claim 1, wherein the cyclone tube extendsinto the bucket so as to form a rim having openings for regulating anamount of liquid entering into the cyclone tube.
 8. A bagless vacuumcleaner, comprising a cyclonic separator having a cyclone tube, and abucket for containing a liquid, wherein in the bucket there is a bodyhaving a center in line with a center of the cyclone tube, a shape ofthe body being or approximating a mushroom-shape.
 9. A bagless vacuumcleaner as claimed in claim 8, wherein the body has a part having asmaller diameter than a largest diameter of the body, a height of thepart corresponding to an intended level of the liquid.
 10. A baglessvacuum cleaner as claimed in claim 8, wherein a diameter of the bucketis at least 2 times a diameter of the cyclone tube.
 11. A bagless vacuumcleaner as claimed in claim 8, wherein the diameter of the bucket is 2.5times the diameter of the cyclone tube.
 12. A bagless vacuum cleaner asclaimed in claim 8, wherein the diameter of the bucket is at least 2.8times a distance between the bottom of the bucket to an end of a vortexfinder of the cyclonic separator.
 13. A bagless vacuum cleaner asclaimed in claim 8, wherein the diameter of the bucket is at least 3times the distance between the bottom of the bucket to the end of avortex finder of the cyclonic separator.
 14. A bagless vacuum cleaner asclaimed in claim 8, wherein the cyclone tube extends into the bucket soas to form a rim having openings for regulating an amount of liquidentering into the cyclone tube.